1. Field of the Invention
This invention relates to a temperature control method and apparatus applicable to machines and has particular application to dies and to moulding of articles using dies in processes such as injection moulding, thermoforming, vacuum forming metal die casting and the like.
2. Description of Related Art
The invention will be described with respect to an application but it is not intended that the concept should be constrained simply to that application.
It is well known that a die can be kept within an acceptable temperature range by use of water passing through passages in the die to a separate heat exchange station.
One of the challenges in the design of dies is to ensure that the working parts of the die have sufficient access to cooling water. This can at times be very difficult indeed if, for instance, there is very little room for appropriate passages for water to be transported to and from a location in sufficient volume.
Such a challenge of keeping the working parts of a die within an acceptable range of temperatures is no small matter and can involve considerable costs in the manufacturing and commissioning of a die. One of the problems experienced is that unless the water is demineralised which is generally uneconomic because of the volume of replacement water needed, then scale build up will occur which again can be costly to treat and can lead to reduced efficiency in cooling over time.
A further problem is the corrosion in the cooling passages caused by their exposure to aerated cooling water.
Further the efficiency of cooling can be a very significant factor in the repetition rate of use of a die. If there were a more efficient way of cooling the die may be able to be used at greater repetition rates which is significant as far as costs of production using the die are concerned.
Further uneven cooling rates between different portions of a moulding die can cause distortion of the moulded parts for which rectification or compensation can be costly.
It is an object of this invention to propose an alternative way to effect temperature control of a machine which at least reduces some of the above difficulties.